Abstract: Refining and chemical enterprises face significant challenges in low-temperature waste heat recovery, characterized by a large variety and volume of heat sources but a scarcity of low-temperature heat sinks. Taking an aromatics refinery as a case study, the rigorous full-process simulations of its 14 major process units were carried out using Aspen Plus software. The results reveal that the total waste heat resources of the plant at or above 90 °C amount to 2074.2 GJ/h, primarily concentrated in the 1# and 2# aromatics adsorption separation units. In contrast, the heat sink capacity at or below 90 °C is only 213.5 GJ/h. Consequently, the internal balance rate for low-temperature waste heat is merely 10.3%, indicating extreme difficulty in waste heat recovery.To address this, themeasures such as producing hot water for external supply, generating and subsequently boosting the pressure of low-pressure steam for pipeline supplementation, and implementing process heat integration both within and across units were implemented. These strategies collectively utilized 1336.2GJ/h of waste heat, increasing the overall low-temperature waste heat utilization rate to 64.2%.

Key words: process unit, waste heat, heat resource, heat sink, upgrade and utilization